(1) Field of the Invention
This invention relates to fast frame recorder apparatus for providing slow motion replay and, more particularly, to a technique and apparatus for facilitating the set-up of an electronic camera useful with such apparatus.
(2) Description Relative to the Prior Art
Motion analysis apparatus using a fast frame recorder--by which scenes are recorded on magnetic tape at one tape speed and replayed in slow motion at a different tape speed--is known. See Research Disclosure, Item No. 19919, Vol. 199, November 1980, published by Industrial Opportunities Ltd., Homewell, Havant, Hampshire, P09 1EF, United Kingdom and/or U.S. Pat. Nos. 4,322,638, filed on Jan. 16, 1980; 4,322,752, filed on Jan. 16, 1980; 4,330,846, filed on Jan. 30, 1980; U.S. Ser. No. 159,421, filed on June 16, 1980; U.S. Pat. Nos. 4,342,057, filed on June 16, 1980; 4,339,775, filed on June 16, 1980 and U.S. patent application Ser. No. 172,915, filed on July 28, 1980. Such fast frame recorder is comprised of a number of major components among which are a video camera having a solid state imager, a tape recorder, and a cathode ray tube (CRT) display monitor. The camera is capable of producing signals corresponding to selected frame rates of from 60 to about 2,000 per second; the tape recorder, by recording at one tape speed and appropriately slowing down the tape during playback to a certain predetermined speed, down-converts the camera signals, regardless of the camera frame rate, to a nominal frame rate of 60 per second; the CRT display monitor receives the 60 per second frame rate playback signal from the tape recorder and displays the scene is question at an appropriate slow motion depending upon the selected camera frame rate.
The quality of the image displayed on the CRT monitor is affected by a variety of "interrelated" conditions among which are (1) the illumination of the scene that was recorded by means of the camera, (2) the camera focus an depth of field, and (3) the selected frame rate at which the camera was operated. This may be appreciated from, among other things, a realization that at 2,000 frames per second, significantly more scene illumination is necessary than at, say, 60 frames per second, if for no other reason than to produce sufficient charges at the pixel sites of the solid state sensor within the video camera. Too few charges will affect the scene recording one way; too many charges will affect the scene recording a different way. Thus, it had been the practice to implement one of two camera set-up procedures to provide for a good playback display on the CRT monitor. In the first set-up procedure, the camera is run at the selected frame rate, its signal being recorded, down-converted to 60 frames per second, and then played back through the CRT monitor. In the event the display on the monitor is less than satisfactory, the camera is appropriately adjusted, and the whole recording process repeated. This trial and error process is repeated over and over until the resulting monitor display is satisfactory. In the second camera set-up procedure, the camera is run at a frame rate of 60 per second, its output signals being serially applied directly (i.e. in E-to-E fashion) to the CRT monitor. Such bypassing of the recorder is possible because the camera and monitor, in this second set-up procedure, are both operative at the same 60 per second frame rate, i.e. signal down-conversion is unnecessary. The camera is then adjusted to optimize the display at a frame rate of 60 per second. To optimize (as best can be done) the display at other camera frame rates, camera set-up parameters are then calculated based on the set-up parameters which were set when operating the camera at 60 frames per second.
Both of the above-described camera set-up procedures, aside from being arduous and time consuming, are less than satisfactory from the standpoint of assuredly providing the best monitor display. For example, in the first camera set-up procedure, one would never know whether another iteration of record-and-playback would be productive of an even more improved monitor display; in the second camera set-up, camera parameter calculations are, at best, only coarse calculations.